1. Field of the Invention
The present invention relates to pacemakers and monitoring systems. More specifically, the invention relates to a gastrointestinal pacemaker stimulatory system that is able to sense and variably pace motor activity of the intestinal tract, having an optional delivery/removal port for administration or removal of fluids or recording systems, suitable for use in humans and in animals.
2. Related Art
The gastrointestinal tract is responsible for an essential step in the digestive process, the reception of nutrition in the human body. Nutrition is received by absorbing mucosa in the gastrointestinal tract, using a very complex mechanism. An important element of the digestive process is intestinal peristalsis, the coordinated and self-regulated motor activity of the intestinal tract. Peristalsis is accomplished through a coordinated combination of electrical, chemical, and hormonal mediation, possibly in addition to other unknown mechanisms.
It is known that many diseases and maladies can affect the motor activity of the gastrointestinal tract, causing malfunction of the digestive process. Such diseases include diabetesmellitus, scleroderma, intestinalpseudo-obstruction, ileus, and idiopathic gastroparesis. Other maladies such as tachygastria or bradiagastria can also hinder coordinated muscular motor activity of the bowel.
The undesired effect of these conditions is a reduced ability or complete failure to efficiently propel intestinal contents down the digestive tract. This results in malassimilation of liquid or food by the absorbing mucosa of the intestinal tract. If this condition is not corrected, malnutrition or even starvation may occur. Whereas some of these disease states can be corrected by medication or by simple surgery, in most cases treatment with drugs is not adequately effective, and surgery often has intolerable physiologic effects on the body.
It is known that motor activity can be recorded as electrical activity of the muscle. Traditionally, motor activity has been measured using recording electrodes placed directly on the muscle of the intestinal tract, or on the skin external to the intestinal tract. For example, electrocardiograms measure the electrical activity of the heart in this manner.
Presently, however, there is no known endoscopically or surgically placed device to stimulate, record, or intelligently alter the muscular contractions of the intestinal muscles from the intraluminal mucosa of the intestinal tract for the purpose of interventional electrical medical therapy, thereby efficaciously altering movement of nutrients through the intestinal tract. Therefore, there is a need in the art for a system and method to properly pace intestinal motor activity for correcting ineffective or absent propulsive electrical muscular activity of the gastrointestinal tract.
3. Medical Background
Normal Gastric Pacemaker Activity. The normal contractile activities of the stomach are coordinated and controlled by myoelectrical activities, termed electrical control activity or pacesetter potentials [Ref. 1]. The normal gastric pacemaker rhythm in man is approximately 3 cpm (cycles per minute) , with the normal range generally considered to be from 2.5-3.6 cpm [Refs. 2-4]. The underlying mechanisms which control and modulate the pacesetter potential [Ref. 1] will not be discussed here.
Abnormal Gastric Pacemaker Activity. Abnormal gastric pacemaker activities have been detected in numerous clinical conditions: diabetic and idiopathic gastroparesis [Refs. 5,6], dyspepsia [Ref. 7], intestinal pseudo-obstruction [Ref. 8], eating disorders [Ref. 9], nausea and gastric ulceration [Ref. 10], nausea of pregnancy [Ref. 11], and motion sickness [Ref. 12]. Most of these conditions are associated with gastric disorders and symptoms of nausea, indigestion, vague epigastric distress, anorexia and vomiting.
Tachygastrias are abnormally fast gastric dysrhythmias ranging from 3.6-9.9 cpm [Refs. 11, 12]. Bradygastrias are abnormally slow gastric dysrhythmias ranging from 1-2.5 cpm [Ref. 13]. Arrhythmias are flatline signals in which no discernible waves are detected [Ref. 11]. These gastric dysrhythmias have been detected non-invasively with cutaneous electrodes as well as with invasive methods using mucosal or serosal electrodes [Refs. 4, 14, 15].
TABLE 1 (below) lists clinical entities in which gastric dysrhythmias have been detected. Many of these entities are chronic ailments which are poorly understood. The gastropareses in particular are thought to be neuromuscular diseases of the stomach which result in delayed gastric emptying and the typical symptoms of nausea, anorexia and vomiting. These entities often respond poorly to drug therapy.
However, in certain individuals with chronic symptoms and gastric dysrhythmias, pharmacological therapy has resulted in eradication of the gastric dysrhythmias and re-establishment of the normal 3 cpm gastric pacemaker rhythm [Ref. 5]. In diabetic patients with gastroparesis, the re-establishment of 3 cpm pacemaker rhythms was associated with the reduction in symptoms, but gastric emptying was not improved. The concept has been proposed that the presence of a normal 3 cpm gastric rhythm is more important to improvement in symptoms than the rate of gastric emptying per se [Ref. 5].
Applicant infers from recent reports [Ref. 4] that pacing the human stomach is feasible. Pacing has been considered with respect to symptoms and gastric emptying in several patients with post-operative distention or gastroparesis [Refs. 16, 17]. However, the stimulus parameters for gastric pacing are not worked out.
In review of the medical and surgical literature, the only known way pacing of the human stomach has involved placement of cardiac pacing wires into the muscle layers of the stomach at the time of laparotomy. The laparotomies were performed primarily for cholecystectomy or for placement of a feeding tube in the jejunum.
There is apparently no known method for convenient placement of pacemaker wires or electrodes for recording gastric myoelectrical activity from the gastric mucosa. A system for the percutaneous and endoscopic placement of such a system would thus be a novel advance for pacing the stomach's electrical activity or for recording myoelectrical activity from the stomach. The present invention offers these possibilities in a safe, quick and convenient package.
TABLE 1 ______________________________________ GASTRIC DYSRHYTHMIAS ASSOCIATED WITH CLINICAL CONDITIONS ______________________________________ Tachygastrias (4-9.9 cpm myoelectrical pattern) 1. Gastroparesis (Diabetic, Idiopathic, Ischemic) 2. Intestinal pseudo-obstruction 3. Nausea of pregnancy 4. Functional dyspepsia -dysmotility type with normal gastric emptying* 5. Gastric ulcers (acute) with nausea 6. Postoperative Acute post-op with ileus Post-cholecystectomy (Roux-en-Y reconstructions 10-13 cpm small bowel frequencies) 7. Eating disorders - anorexia nervosa 8. Premature infants 9. Drug-induced (Glucagon, Epinephrine, Morphine sulfate) 10. Functional (idiopathic) dyspepsia - dysmotility type Tachyarrhythmias (mix of tachygastrias and bradygastrias) 1. Motion sickness 2. Idiopathic gastroparesis Bradygastrias (1-2 cpm myoelectrical pattern) 1. Gastroparesis (Diabetic, Idiopathic, Ischemic, Post- operative (gastric resection)) 2. Intestinal pseudo-obstruction 3. Nausea of pregnancy 4. Functional dyspepsia - dysmotility type with normal gastric emptying* 5. Eating disorders - bulimia nervosa 6. Drug-induced Epinephrine Arrhythmias (flatline EGG pattern) 1. Nausea of pregnancy 2. Hyperemesis gravidarum 3. Drug-induced - epinephrine 4. Bilroth I or II with gastroparesis 5. Bilroth I or II with no symptoms (normal 3 cpm EGG pattern) ______________________________________ *Normal 3 cpm EGG pattern is seen in obstructive gastroparesis **Normal 3 cpm EGG pattern is seen in functional dyspepsia reflux type